The present invention will be described for ensuring the presence of a snap ring during manufacture of a vehicle transmission system. However, the present invention may be used for ensuring the presence of the snap ring during manufacture of any other object of article of manufacture, as would be apparent to one of ordinary skill in the art from the description herein.
Referring to FIG. 1, a bearing 102 is coupled to a part of a mission case 104 holding a vehicle transmission system. The bearing 102 fits within a mission case bearing hole 106. The bearing 102 has a snap ring groove 108. A snap ring fits within the snap ring groove 108, and the snap ring holds the bearing 102 to the mission case 104 within the mission case bearing hole 106.
During manufacture of the vehicle transmission system, the bearing 102 is initially placed around a spreader shaft 110. A snap ring 112 is initially placed around a plurality of fingers, including a first finger 114, a second finger 116, a third finger 118, and a fourth finger 120.
During manufacture of the vehicle transmission system, the snap ring 112 and the plurality of fingers 114, 116, 118, and 120 are disposed within the mission case bearing hole 106. The spreader shaft 110 holding the bearing 102 is lowered toward the plurality of fingers 114, 116, 118, and 120. As the spreader shaft 110 makes contact with the plurality of fingers 114, 116, 118, and 120, the plurality of fingers are pushed outward such that the diameter of the snap ring 112 expands. Such an expansion of the snap ring 112 allows the snap ring 112 to fit around the bearing 102 as the bearing 102 is lowered into the mission case bearing hole 106.
In addition, as the spreader shaft 110 makes contact with the plurality of fingers 114, 116, 118, and 120, the plurality of fingers are pushed downward. In this manner, when the snap ring 112 is aligned with the snap ring groove 108 on the bearing 102, the fingers are moved away such that the snap ring 112 contracts back to a smaller diameter to fit snugly around the snap ring groove 108 on the bearing 102. Also, at this point, the snap ring is holding in proper place the bearing 102 within the mission case bearing hole 106 of the vehicle transmission system.
During manufacture of the vehicle transmission system, the snap ring 112 may be mistakenly left out. A human operator may fail to place the snap ring 112 around the plurality of fingers 114, 116, 118, and 120 by human error. Alternatively, an automated assembly machine may fail to place the snap ring 112 around the plurality of fingers 114, 116, 118, and 120 because of machine malfunction.
However, a vehicle transmission system requires a snap ring to hold a bearing in place. Without a snap ring holding the bearing in place, the vehicle transmission system may fail to operate properly. However, because the snap ring is disposed inside the mission case 104, the presence of the snap ring cannot be detected visually during further steps in the manufacturing process of the vehicle transmission system.
Accordingly, a magnichanical sensor is disposed on at least one of the plurality of fingers 114, 116, 118, and 120 for monitoring the presence of the snap ring 112 during manufacture of the vehicle transmission system. Such a magnichanical sensor is described in a first copending patent application having Ser. No. 09/235,725 and filing date of Jan. 22, 1999, and having the common inventor and assignee herewith. Such a magnichanical sensor is also described in a second copending patent application having Ser. No. 09/235,890 and filing date of Jan. 22, 1999, and having the common inventor and assignee herewith. The first copending patent application having Ser. No. 09/235,725 and the second copending patent application having Ser. No. 09/235,890 are incorporated herewith by reference.
Referring to FIG. 2A, a first magnichanical sensor 202 is disposed within an opening 204 on a side of a finger 206. Referring to FIGS. 1 and 2A, the finger 206 is one of the plurality of fingers 114, 116, 118, and 120. The opening 204 is disposed on the side of the finger that faces toward the snap ring 112.
The magnichanical sensor 202 includes a magnetic field generator 208 and a magnetic switch 210. The magnetic field generator 208 may be a rare earth magnet for example or any other source of magnetic field, as known to one of ordinary skill in the art. The magnetic switch 210 may be a reed switch or a hall effect switch for example or any other type of switch which opens and closes depending on the configuration of a magnetic field, as known to one of ordinary skill in the art. In addition, the magnichanical sensor further includes a snap ring presence indicator 212 that is coupled to the magnetic switch 210.
Referring to FIG. 2A, a first position of the magnetic field generator 208 is aligned with a second position of the magnetic switch 210 such that the magnetic field (shown by dashed lines in FIG. 2A) generated by the magnetic field generator 208 maintains the magnetic switch 210 to be open. When the magnetic switch 210 is open, the snap ring presence indicator 212 determines that a snap ring is not present around the plurality of fingers 114, 116, 118, and 120.
Referring to FIGS. 1 and 2B, when the snap ring 112 is placed around the plurality of fingers 114, 116, 118, and 120, the snap ring 112 which is comprised of a ferrous material alters the magnetic field generated by the magnetic field generator 208. Note that elements having the same reference number in FIGS. 2A and 2B refer to elements having similar structure and function. Such an alteration of the magnetic field (shown by dashed lines in FIG. 2B) causes the magnetic switch 210 to transition from being open to being closed. When the magnetic switch 210 is closed, the snap ring presence indicator 212 determines that the snap ring 112 is present around the plurality of fingers 114, 116, 118, and 120.
In this manner, the magnichanical sensor 202 detects for the presence of the snap ring 112 during manufacture of the vehicle transmission system. If the snap ring is determined to be not present as illustrated in FIG. 2A during placing of the bearing 102 into the mission case 104, an alarm alerts an operator to this undesirable situation.
Alternatively, referring to FIG. 3A, the first position of the magnetic field generator 208 may be aligned with the second position of the magnetic switch 210 such that the magnetic field (shown by dashed lines in FIG. 3A) generated by the magnetic field generator 208 maintains the magnetic switch 210 to be closed. Note that elements having the same reference number in FIGS. 2A and 3A refer to elements having similar structure and function. When the magnetic switch 210 is thus closed, the snap ring presence indicator 212 determines that a snap ring is not present around the plurality of fingers 114, 116, 118, and 120.
Referring to FIGS. 1 and 3B, when the snap ring 112 is placed around the plurality of fingers 114, 116, 118, and 120, the snap ring 112 which is comprised of a ferrous material alters the magnetic field generated by the magnetic field generator 208. Note that elements having the same reference number in FIGS. 3A and 3B refer to elements having similar structure and function. Such an alteration of the magnetic field (shown by dashed lines in FIG. 3B) causes the magnetic switch 210 to transition from being closed to being open. When the magnetic switch 210 is open, the snap ring presence indicator 212 determines that the snap ring 112 is present around the plurality of fingers 114, 116, 118, and 120.
Alternatively, a first type of magnetic switch may be open while a second type of magnetic switch would be closed when a snap ring is present. Any type of magnetic switch which are in different states between the situations of the snap ring being not present and the snap ring being present may be used in the magnichanical sensor 202, as would be apparent to one of ordinary skill in the art from the description herein.
In any case, the magnichanical sensor 202 must be fabricated for proper operation on one of the plurality of fingers 114, 116, 118, and 120 during manufacture of the vehicle transmission system. A proper polarity of the magnetic field generator 202 within the opening 204 is determined. In addition, the first position of the magnetic field generator 208 is properly aligned with the second position of the magnetic switch 210.